The Importance of Protein in a Balanced Diet
What Is Protein, and Why Do I Need It?
Proteins are critical components of all tissues in the human body and have crucial roles in metabolism, immunity, fluid balance, and energy. The building blocks of protein are called amino acids, which are divided into two groups: essential and non-essential. Essential amino acids are ones the body cannot produce. Therefore, it is essential we consume them from food. Non-essential amino acids can be synthesized by the body, so we do not need to consume them from food. The amount of essential amino acids in a protein will determine whether is it a complete (high-quality) protein or incomplete (low-quality) protein. Complete protein sources are typically derived from animal products such as eggs, meat, poultry, fish, and dairy. Soybeans are the most complete source of plant-based protein. Other plant-based sources of (incomplete) protein include legumes, whole grains, nuts, and seeds. Eating a well-balanced diet (even for vegetarians and vegans) can help ensure we are getting adequate amounts of protein and all essential amino acids.
How Much Protein Do I Need?
The Recommended Dietary Allowance (RDA) of protein is 0.8g per kilogram of body weight per day. The recommended percentage of calories that should come from protein is between 10 to 35%. One gram of protein has 4 calories. So if an individual is consuming 2,000 calories daily, they should be consuming between 50 to 175g of protein. The average American consumes well above the RDA of protein.
Do Athletes Need More Protein?
Yes. Athletes do benefit from more protein than inactive individuals for multiple reasons. Regular exercise can both stimulate muscle growth and cause tissue damage, which is repaired by protein. Exercise also increases the transport of oxygen to tissues, which is carried out by a protein called hemoglobin. We also use protein for a small amount of energy. Protein can be converted to glucose, the body’s preferred energy source, so it helps prevent hypoglycemia (low blood sugar).
The Academy of Nutrition and Dietetics recommends 1.2 to 2.0 grams of protein per kilogram of body weight per day for athletes. Endurance athletes should consume 1.2 to 1.4 grams per kilogram, while strength athletes should aim for 1.6-2 grams per kilogram.
Is too much harmful? The body cannot store excess protein. Protein consumed in excess will be either be used for energy (typically only during times of low carbohydrate intake or starvation) or converted to fat. Therefore, it is possible to gain weight on a high-protein diet if the individual is consuming more calories than necessary.
High-protein diets are not advised for people with chronic kidney disease or declined kidney function (or only one kidney). Medical evidence does not suggest that eating more protein increases the risk of kidney disease in healthy individuals. High-protein diets have been tied to high cholesterol only when the predominant source of protein comes from animal foods high in saturated fat. It is important to note that individuals (especially athletes) on a high-protein diet also require more water to help flush excess urea (a waste product from the breakdown of protein) from the kidneys.